1. Field
Example embodiments relate to a gas-adsorbing material and a vacuum insulation material using the gas-adsorbing material. The gas-adsorbing material may be used in various fields in which a vacuum is maintained, such as for removing trace gases, a gas in a fluorescent lamp, and the like.
2. Description of the Related Art
There has been increasing interest in a vacuum insulation material having improved insulating effects for electronic appliances, machinery, and equipment in order to conserve energy. A vacuum insulation material may be manufactured by covering a core material having micropores (such as glass wool, silica powder, or the like) with an exterior material having gas barrier properties, and then sealing the inside of the exterior material under a reduced pressure. To maintain the improved insulating effect of the vacuum insulation material for a relatively long period of time, adsorbing materials for removing an aqueous vapor or gas (such as oxygen, nitrogen, and the like) that infiltrates into the vacuum insulation material are sealed with the core material in the vacuum insulation material under a reduced pressure.
Among the adsorbing materials, a chemically adsorbing material irreversibly fixing and adsorbing moisture may be appropriate for the vacuum insulation material. One example of such a moisture adsorbing material is calcium oxide (CaO). However, a moisture adsorbing material such as the calcium oxide may not adsorb oxygen and nitrogen which may permeate through the exterior material of the vacuum insulation material from the air.
A metallic material formed of a barium getter or a ternary alloy of zirconium-vanadium-iron may be used as an adsorbing material capable of adsorbing oxygen or nitrogen. However, these adsorbing materials need to be activated at a relatively high temperature of greater than or equal to about 400° C. under a reduced pressure environment. To complicate matters, such adsorbing materials should not be heated, because the reduced pressure environment is set by using an exterior material by multi-layering a plastic film and a metal foil, and the exterior material may be molten and broken.
An adsorbing material used to remove an impurity gas such as nitrogen from a purifying subject gas may be a ZSM-5-type zeolite where a copper ion is exchanged (e.g., a vacuum insulation material where copper ions are introduced into a ZSM-5-type zeolite by a conventional ion exchange method and a heat treatment is performed to activate nitrogen adsorption activity).
However, moisture essentially coexists in an insulation structure such as vacuum insulation material. In copper ion exchanged ZSM-5-type zeolite, copper ions that are nitrogen active sites have higher reaction activity with moisture than nitrogen and are oxidized by moisture to form copper hydroxide and become inactive to nitrogen. A maximum nitrogen adsorption amount of the vacuum insulation material at an equilibrium pressure of 10 Pa is about 0.238 mol/kg (5.33 cc-STP/g).
A vacuum insulation material may be used wherein a moisture adsorbing material covers a ZSM-5-type zeolite including exchanged copper ions to avoid effects caused by moisture. However, the ZSM-5-type zeolite including exchanged copper ions and a ratio of silica relative to alumina of greater than or equal to 8 and less than or equal to 25 has a relatively large adsorption rate for moisture. Accordingly, there are problems that when the ZSM-5-type zeolite is covered by a moisture adsorbing material under an inert gas, it may be inactivated by a trace amount of moisture in the inert gas.